← ACARA Digital Technologies Years 9–10

The TCP/IP four-layer model

A four-layer plan for network communication: application (HTTP), transport (TCP, UDP), internet (IP) and network access (Ethernet, Wi-Fi). Each layer has its own job.

Part of: ACARA Digital Technologies Years 9–10 — Networked Systems and Access Control — Module 50, WA Computer Science ATAR Year 11 — Network Communications — Module 26, WA Computer Science ATAR Year 11 — Cyber Security — Module 20

Understanding The TCP/IP four-layer model in ACARA Digital Technologies Years 9–10

What it does: The Internet Protocol (IP) gives packets source and destination IP addresses so routers can send them towards their destination. Ethernet (wired) and Wi-Fi (wireless) handle the physical connection between devices on the same local network, which is the job of the network access layer. HTTP is used by web browsers and servers, so it sits at the top, in the application layer. TCP and UDP are transport layer protocols. IP is the protocol at the internet layer. Layers split the work. Each one has a separate job, so protocols can be changed or improved without redoing everything.

Common mistakes: IP works at the internet layer. The transport layer uses TCP or UDP, so line 2 should be 'transport: TCP'. Ethernet belongs to the network access layer. A web browser's request uses HTTP at the application layer, so line 2 should be 'application layer: HTTP'.

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This module's key terms are also in a printable crossword (Modules 41–55) and word search (Modules 12–55).

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Learning

Duo

Which layer of the TCP/IP model does HTTP belong to?

Network access layerApplication layer

Matches

Transport layer: IP

↓

IP is not a transport layer protocol. IP belongs to the internet layer. The transport layer uses TCP and UDP.

Applying

Meanings

Term

TCP/IP model

Meaning

A four-layer plan for network communication: application (HTTP), transport (TCP, UDP), internet (IP) and network access (Ethernet, Wi-Fi). Each layer has its own job.

Practice

Application: HTTP

Testing

Gaps

Application layer protocol:

Check Answer

Spots

1application: HTTP

2transport: IP

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Quick Questions

1. Which layer of the TCP/IP model does HTTP belong to?

A. Application layer ✓

B. Network access layer

HTTP is used by web browsers and servers, so it sits at the top, in the application layer.

2. Which statement about TCP and UDP is correct?

A. They both work at the transport layer ✓

B. They both work at the internet layer

TCP and UDP are transport layer protocols. IP is the protocol at the internet layer.

3. Which layer uses IP addresses to send packets between networks?

A. Transport layer

B. Internet layer ✓

The internet layer uses IP to address packets and move them between networks. The transport layer handles delivery between programs.

4. Ethernet and Wi-Fi belong to which layer?

A. Application layer

B. Network access layer ✓

Ethernet (cables) and Wi-Fi (wireless) move data over the physical link, which is the job of the network access layer.

5. How many layers does the TCP/IP model have?

A. Four ✓

B. Seven

TCP/IP has four layers: application, transport, internet and network access. The seven-layer model is a different one (OSI).

Match the Pairs

Application layer: HTTP → The top layer, where programs such as web browsers use protocols like HTTP to request and send data.

Transport layer: TCP, UDP → The layer that manages delivery between devices: TCP is reliable and checks data arrives, UDP is faster but does not check.

The internet layer addresses packets and finds a route for them across networks. → Internet layer: IP

The network access layer sends data over the physical link, such as a cable or radio signal, to the next device. → Network access layer: Ethernet, Wi-Fi

Transport layer: IP → IP is not a transport layer protocol. IP belongs to the internet layer. The transport layer uses TCP and UDP.

Network access layer: HTTP → HTTP is not a network access protocol. HTTP belongs to the application layer. The network access layer uses Ethernet and Wi-Fi.

Key Term

TCP/IP model

A four-layer plan for network communication: application (HTTP), transport (TCP, UDP), internet (IP) and network access (Ethernet, Wi-Fi). Each layer has its own job.

Fill in the Blanks

1. Application layer protocol: HTTP

Hint: Type the protocol that web browsers use to request and receive web pages.

2. Transport layer: TCP and UDP

Hint: Type the other transport protocol, the faster one that does not check delivery.

3. Internet layer protocol: IP

Hint: Type the two-letter protocol that addresses packets and moves them between networks.

4. Network access layer: Ethernet and Wi-Fi

Hint: Type the wireless technology that sits alongside wired Ethernet in the bottom layer.

5. Layer 1: application (HTTP) Layer 2: transport (TCP, UDP) Layer 3: internet (IP)

Hint: Type the name of the layer that holds TCP and UDP.

Spot the Error

Question 1

A application: HTTP

B transport: IP

C internet: IP

D network access: Wi-Fi

Line B — IP works at the internet layer. The transport layer uses TCP or UDP, so line 2 should be 'transport: TCP'.

Question 2

A browser requests a page

B application layer: Ethernet

C transport layer: TCP

D internet layer: IP

Line B — Ethernet belongs to the network access layer. A web browser's request uses HTTP at the application layer, so line 2 should be 'application layer: HTTP'.

Question 3

A layers = 4

B top = network access

C next = transport

D then = internet

E bottom = network access

Line B — The application layer is at the top of the TCP/IP model. Network access is at the bottom, so line 2 should be 'top = application'.

Question 4

A HTTP -> application

B TCP -> transport

C IP -> internet

D Ethernet -> internet

E Wi-Fi -> network access

Line D — Ethernet is a network access layer technology. It moves data across a local link. Line 4 should be 'Ethernet -> network access'.

Question 5

A application: apps use HTTP

B transport: splits data, TCP

C internet: sends HTTP pages

D access: sends bits on a link

Line C — The internet layer uses IP to address packets and send them between networks. HTTP pages belong to the application layer. Line 3 should be 'internet: addresses with IP'.

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